Aviation Accident Summaries

Aviation Accident Summary LAX95FA068

SAN LUIS OBISPO, CA, USA

Aircraft #1

N26443

GRUMMAN AA-5A

Analysis

THE ACCIDENT SITE IS ON THE SOUTH FACE OF A MOUNTAIN AT 3,000 FEET MSL. THE MOUNTAIN IS PART OF THE COASTAL MOUNTAIN RANGE WHICH SEPARATES SAN LUIS OBISPO FROM THE GREATER SAN JOAQUIN VALLEY, WHERE THE PILOT'S DESTINATION IS LOCATED. CEILINGS IN THE AREA WERE MEASURED BETWEEN 2,600 AND 2,300 FEET. THE NON INSTRUMENT-RATED PILOT RECEIVED TWO WEATHER BRIEFINGS PRIOR TO DEPARTURE AND WAS ADVISED THAT MARGINAL VFR CONDITIONS EXISTED WITH SAN LUIS OBISPO REPORTING A MEASURED CEILING OF 3,500 BROKEN AND VISIBILITY 10 MILES. THE BRIEFER ADDED AN OBSERVATION FROM AN AIRPORT ABOUT 20 MILES SOUTH OF SAN LUIS OBISPO, WHICH HAD CEILINGS OF 3,000 FEET OVERCAST. THE BRIEFER THEN PROVIDED THE PILOT WITH THE SAN JOAQUIN VALLEY OBSERVATIONS INDICATING CLEAR CONDITIONS BELOW 12,000 FEET. THE PILOT RESPONDED, 'THAT'S GOOD ENOUGH FOR US'. THE PILOT STATED HIS INTENDED CRUISE ALTITUDE AS, 'ABOUT FORTY FIVE HUNDRED FEET ONCE WE GET PAST THESE CLOUDS'. THE BURNED AND FRAGMENTED WRECKAGE WAS SPREAD OVER 260 FEET ON A 10-DEGREE DESCENDING PATH ON THE MOUNTAINSIDE. NO MECHANICAL FAILURES WERE IDENTIFIED IN THE WRECKAGE EXAMINATION.

Factual Information

HISTORY OF FLIGHT On December 30, 1994, about 2130 Pacific standard time, a Grumman AA-5A, N26443, collided with mountainous terrain approximately 18 miles northeast of the San Luis Obispo, California, airport. The aircraft was owned and operated by the pilot and was on a personal cross-country flight to Tulare, California. Instrument meteorological conditions existed at the accident site and no flight plan was filed. The aircraft was demolished in the impact and postcrash fire sequence. The private pilot and his one passenger sustained fatal injuries. Based on airport witness observations, the flight originated at the San Luis Obispo airport on the evening of the accident between 2045 and 2100. The accident site is on the south face of Black Mountain at an elevation of 3,000 feet msl. Black Mountain is part of the coastal mountain range which separates San Luis Obispo from the greater San Joaquin Valley, where the pilot's destination is located. A Federal Aviation Administration (FAA) radar site is located at the summit, which has an elevation of 3,600 feet msl. Ceilings in the area were measured between 2,600 and 2,300 feet. Investigation revealed that the pilot departed Tulare about 1000 on the morning of the accident and flew to San Luis Obispo. The owner of a fixed-base operation (FBO) at Tulare, Valley Air Crafts, reported that he spoke to the pilot just before his departure. The FBO owner stated that as the pilot left Tulare, the visibility was between 1-2 miles in fog. FAA records of preflight weather briefings disclosed that a person who identified himself as the pilot of N26443, twice telephoned the Hawthorne Automated Flight Service Station (AFSS) for weather information on the day of the accident. Transcripts of the briefings are attached to this report. During the first call at 1609, the pilot indicated that he was going to fly from San Luis Obispo to Tulare that evening between 6 and 8 p.m. and asked, "i just wonder if its still going to be v-f-r in tulare or visalia". The AFSS briefer then provided the pilot with a terminal forecast for the closest reporting airport to Tulare (NAS Lemoore), which predicted high, broken cloud conditions and visibilities greater than 6 miles. The pilot responded, " . . . we flew out of there (tulare) this morning and we just beat the fog rolling into tulare". In addition, the pilot said, "its beginning to cloud up here and i dont know what the cloud bottoms and visibility are". The briefer then provided the pilot with the San Luis Obispo terminal forecast valid until 2100 which called for a 3,500 scattered-to-broken cloud condition. The pilot telephoned Hawthorne AFSS again at 2029 for additional weather information for his destination and departure airports. In pertinent part, the pilot was advised that marginal VFR conditions existed with San Luis Obispo reporting a measured ceiling of 3,500 broken and visibility 10 miles. The briefer added an observation from an airport about 20 miles south of San Luis Obispo, which was reporting ceilings of 3,000 feet overcast. The briefer then provided the pilot with the San Joaquin Valley observations indicating clear conditions below 12,000 feet. The pilot responded, "thats good enough for us". In response to a question from the briefer about the pilot's intended cruise altitude, the pilot said, "about forty five hundred feet once we get past these clouds". CREW INFORMATION No personal pilot records were recovered. The pilot's FAA Airman and Medical Certification file maintained by the FAA at the Airman Records Center in Oklahoma City, Oklahoma, were reviewed. The records revealed that the pilot held a private pilot certificate with an airplane single-engine land rating, the most recent issuance of which was dated December 7, 1978. The pilot did not hold an instrument rating. The most recent third-class medical certificate was issued on July 7, 1994, with the limitation that the pilot must have available glasses for near vision while exercising the privileges of his airman certificate. No specific information was available to document the pilot's recent, total, or instrument flight experience. On his last medical application, the pilot reported a total time of 1,065 hours. Information supplied by the maintenance firm which routinely performed work on the aircraft suggests that the pilot flew about 60 hours per year. AIRCRAFT INFORMATION No aircraft maintenance records were recovered. An aircraft maintenance firm, Valley Air Crafts of Tulare, California, was contacted. The owner reported that his company performed the routine maintenance on the aircraft. His records disclosed that an annual inspection was performed on May 18, 1994. At the time of the inspection, the airframe and engine had accrued a total time in service of 1,060 hours. The firm's owner stated that he spoke to the pilot on the morning of the accident as the pilot was departing for San Luis Obispo and the pilot did not report any problems with the aircraft. The aircraft was last fueled about 2030 on the evening of the accident at IFC, a fixed-base operator at the San Luis Obispo airport. The fueling records denote that 15.1 gallons of 80/87 octane aviation fuel were dispensed in the aircraft fuel tanks. The fueler who performed the operation stated that the added fuel topped the aircraft tanks. METEOROLOGICAL INFORMATION The closest official weather observation station is the San Luis Obispo airport, which is located 18 nautical miles southwest of the accident site. The 2050 observation was reporting in part: Measured ceiling 2,600 overcast; visibility 8 miles; temperature 49 degrees Fahrenheit; dew point 43 degrees Fahrenheit; winds calm; altimeter 30.09 inHg. The 2150 observation was reporting in part: Measured ceiling 2,300 broken; visibility 8 miles; temperature 49 degrees Fahrenheit; dew point 42 degrees Fahrenheit; winds 120 degrees at 4 knots; altimeter 30.16 inHg. WRECKAGE AND IMPACT INFORMATION The accident site is on the southern face of Black Mountain at an elevation of about 3,000 feet msl. A path of wreckage debris, ground scars, and burned vegetation were observed on a magnetic bearing of about 280 degrees over a distance of about 260 feet. The orientation of the ground disturbance was noted to be on a descending path of about 10 degrees to the horizontal. The first ground scar was noted to be a thin disturbance in the brush and soil about 200 feet east of the main wreckage mass. Material later associated with the right wing tip was found in this area. The aircraft was extensively fragmented and burned. The right wing separated from the fuselage at the root with aft bending noted on the main spar tube. The outboard 1/3 of the wing separated with aft bending noted on the main spar tube at the separation point. Leading edge damage was noted along the full span. The flap remained attached to the wing structure. The aileron separated from the wing and was found along the wreckage distribution path. The left wing was burned and exhibited leading edge damage in an aft direction back to the spar tube along the full span. The aileron and flap remained attached to the wing structure. The empennage fixed and movable control surfaces remained attached to the structure and were not damaged. Control system continuity could not be established due to the extensive fragmentation and fire damage. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was conducted by the San Luis Obispo County Coroner's Office on January 3, 1995, with specimens retained for toxicological examination. The results of the toxicological examination were negative for alcohol and all screened drug substances. TESTS AND RESEARCH The aircraft was recovered from the accident site and examined in detail on January 18, 1995, at a storage facility at the Santa Paula airport. The propeller remained attached to the engine crankshaft. One blade exhibited leading edge damage, torsional twisting, and chordwise striations. The outboard half of the second blade separated with overload signatures evident. The engine was extensively fire damaged, with complete destruction of the accessory section noted. The carburetor was impact damaged and fragmented. Rotation of the crankshaft produced compression in cylinders No. 1, 2, and 4. Weak compression was observed in the No. 3 cylinder. Accessory gear and valve train continuity was established. The No. 3 cylinder was removed with no unusual operating signatures noted on the internal cylinder walls, piston, or rings. The vacuum pump was fire damaged. It was disassembled; the rotor and vanes were intact. ADDITIONAL INFORMATION The wreckage was released to representatives of the registered owner at the conclusion of the examination on January 18, 1995.

Probable Cause and Findings

the pilot's intentional flight into an area of known marginal weather conditions during a night cross-country flight and the flight's subsequent inadvertent entry into instrument meteorological conditions at an altitude insufficient to remain clear of the surrounding terrain.

 

Source: NTSB Aviation Accident Database

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